A variety of containers exist that are individually suited to packaging, holding, shipping and storing a great many different types of contents. For example, an envelope is a special type of container used to store and ship enclosures (business letters, invoices, photographs, advertisements, etc.). Another example is a paper carton that is used to store a given number of packages of cigarettes. Still other examples are video and audio tape boxes which are used to store and ship tapes. Thus, it is apparent that there is a great diversity in the types, shapes and sizes of containers. Typically, the containers are made from a plurality of panels which are arranged to encompass a desired volume of space having a desired configuration. To gain access to the inside of the container it is necessary for at least one panel to be moveable with respect to the remaining panels. This is usually accomplished by a hinge arrangement where the moveable panel is connected to an adjacent panel along one edge. However, other arrangements are commonly used depending upon the application.
Often times, in placing contents into containers or in taking contents out of containers, there is a need for automatic equipment. Typically, cigarette manufacturers, tape manufacturers and high volume mailers utilize a great deal of automation to reduce costs and speed production. Necessarily then, the container must be opened before any later tasks can be performed. As a result of this need, a great many different types of container opening systems have been developed. Outlined below is a description of some of the container opening systems that are known in the art. Although most of the systems are from the envelope opening art, the concepts and underlying technology are similar and adaptable to those found in other disciplines using different containers.
Envelope handling machines are well known in the art. Typical types of envelope handling machines include: mailing machines, inserters, sorters and incoming mail handling machines. Frequently, these machines have the need to open an envelope so that a desired task or operation can be performed. For example, in an inserter it is necessary to open the envelope so that an enclosure can be fed into the envelope. Another example is in incoming mail handling machines where it is necessary to open the envelope so that the enclosures (possibly placed into the envelope by an inserter) can be removed from the envelope.
Many different systems exist to open envelopes and containers. Early systems were mechanical in nature and relied upon arms or fingers to reach inside the envelope in order to open it. Examples of such systems are shown in U.S. Pat. Nos. 4,337,609, 5,255,498, 5,191,751, and 5,247,780 all of which are assigned to the assignee of the present invention. Although many improvements have been made over the years and such systems are generally effective, they still suffer from certain drawbacks. First, the envelopes are susceptible to damage by the moving parts of the system. Despite efforts to the contrary, inevitably envelopes are still torn or crushed by such systems. Second, because such mechanical systems are sensitive to wear, they need frequent recalibration and/or preventive maintenance.
Still other systems use a combination of vacuum and mechanical technologies to open envelopes and other containers. Examples of such systems are shown in U.S. Pat. Nos. 4,486,013, 4,776,152, and 5,052,168. In these systems, moveable sucker feet are brought into and out of engagement with the container by means of any suitable mechanical device. Additionally, the sucker feet are directly connected by tubes to a vacuum source in order to create the vacuum necessary to grab the envelope. Although these systems have less physical contact with the envelope than the pure mechanical systems, they too suffer from drawbacks. First, because the vacuum tubes are carried along with the sucker feet, they are in constant motion. In high throughput operations where the container opening apparatus performs many thousands of cycles per hour, there is a risk that the vacuum tube will shake itself loose from the sucker foot. Second, the vacuum tube is susceptible to wear as it rubs up against adjacent components cycle after cycle. In an extreme case, the vacuum tube may even become tangled. All of these problems result in a loss of vacuum at the sucker foot where it is needed and require operator intervention to correct.
Accordingly, there is a need for a container opening apparatus that provides reliable operation without the risk of damage to the container, risk of loss of vacuum or frequent maintenance.